The Pentagon Attack:
What the Physical Evidence Shows

by
Jim Hoffman
Version 0.9, March 28, 2006

Introduction

The theory that the Pentagon was not hit by a Boeing 757
(the kind of plane that Flight 77 was)
is promoted by the most widely distributed books, videos,
and other media challenging the official account of the 9/11 attack.
The no-Boeing theory forms the central thesis of
Thierry Meyssan's books
L'effroyable Imposture (The Frightening Fraud),
and Le Pentagate;
is featured by the videos
Painful Deceptions,
9/11 In Plane Site,
and
Loose Change;
and is the subject of the Flash animation
9/11 Pentagon Strike.
These pieces have been distributed worldwide
in quantities reaching into the millions,
thanks to a combination of excellent production values,
entertaining and captivating styles of presentation,
and expert, well-financed marketing.
The work of 9/11 researchers who do not embrace the no-Boeing theory
has been eclipsed in every medium except the web.

That essay presents a cumulative argument against the no-Boeing theory
using each of these perspectives.
Critics of this essay failed to acknowledge this and instead
zeroed in on one point or another to highlight it as if the entire
case against the no-Boeing theory hinged on that point.
For example, several critics have misstated my position as
relying exclusively on the accounts of eyewitnesses,
ignoring my detailed examination of the 'physical evidence case'
for the no-Boeing theory.

In this essay I look exclusively at the physical evidence
of the Pentagon attack --
post-crash photographs and verifiable information about the
building, the Boeing 757-200 aircraft,
and the physics of aircraft crashes based on case studies.
In some cases I mention elements of eyewitness accounts,
but only to frame my analysis of what the photographs show
about the crash.
I show that the physical evidence is consistent with the crash of a 757,
noting flaws in popular arguments to the contrary.

The many eyewitness accounts of the Pentagon attack
constitute a rich body of evidence that strongly supports
the conclusion that the attack plane was either a Boeing 757
or a very similar aircraft.
The physical and eyewitness evidence are thus mutually corroborating,
a fact that is obscured by common errors in evaluating
the physical evidence.
Many researchers have dismissed the body of eyewitness evidence
out of hand, primarily for two reasons:

Allegations that the body of witness evidence as a whole
is plagued by bias, contamination, and unreliability
(addressed
here)
have been widely promoted
and have not been effectively countered,
apparently because
the ponderous volume of the witness reports discourages analysis.

Assertions that
physical evidence trumps witness evidence in any crime investigation
have fostered a reflexive disdain for witness evidence
while lending a false sense of infallibility to arguments based
on photographs.

Factors such as these have contributed to the creation of a false
dialectic, which has eyewitness evidence supporting the Boeing theory
and physical evidence supporting the no-Boeing theory.
By focusing on the physical evidence here,
I hope to sidestep that dialectic and clarify what conclusions
the physical evidence actually supports.

Debris is Consistent with a Jetliner Crash

The Pentagon attack left debris scattered over a wide area.
Judging from the
dimensions of punctures in the facade
the vast majority of debris ended up inside of the building.
Nonetheless, the few photographs that show portions of the
lawn near the building show an extensive debris field,
easily accounting for the portions of a 757 that
did not penetrate the building.
Although no photographs show large pieces of aircraft,
it is not reasonable to expect large pieces to have survived intact
given the nature of the crash.

High-Speed Crashes Reduce Aircraft to Small Pieces

Few people have direct experience with the results of
high-speed collisions of aircraft into strong barriers.
Most aircraft accidents occur shortly after takeoff
or during attempted landings,
and do not completely destroy the aircraft.
In contrast, uncontrolled crashes into terrain usually
reduce aircraft into fine debris,
leaving little if any parts identifiable by casual visual inspection.
The debris fields of several jetliner crashes
pictured here
show the surprising paucity of apparent debris
many crashes produce.
Crashes of aircraft into buildings also typically leave
little in the way of large debris, as the December 5, 2005
crash of a C-130 into an apartment building
in Iran illustrates.

It is noteworthy that many crashes that left very little to no
large recognizable pieces involved much lower impact speeds
than the Pentagon attack.
Since the Iranian C-130 was attempting to land,
its airspeed was probably less than 150 mph.

Debris from the Attack Plane is Widely Distributed

The Pentagon attack produced damage covering an area
inside and outside the building
totaling tens of thousands of square feet.
Available photographs document only small portions of this area,
but nonetheless show significant quantities of debris.

Photographs show a debris field covering a portion of the lawn
directly north of the central impact region of the facade,
and extending to the heliport about 120 feet from the facade.
Most of the debris in this field is small,
but some photographs show pieces as big as four feet across.

Photographs of Interior Wreckage Are Sparse

Given the extent and shape of punctures in the Pentagon's facade,
it is reasonable to expect that well over 90 percent of
the mass of a 757 would have ended up inside the building.
Unfortunately, there are relatively few public photographs of
the interior of the Pentagon after the crash,
and there are very few photographs showing the interior
before the rescue and recovery operations had removed debris.

Skeptics of the crash of Flight 77 into the Pentagon have
argued that the lack of public photographs showing
airliner seats, bodies, and luggage
is evidence against the crash of Flight 77.
This argument is based on several assumptions,
none of which are supported.

The seats, passengers, and luggage would have survived the
over 500-mph crash and subsequent fires
in a form yielding to easy identification in photographs.

Remains of the seats, passengers, and luggage would have
been photographed and the photographs would have been made public.

The baselessness of the second assumption becomes particularly apparent
when one notes that nearly the entire fuselage
(containing the seats, passengers, and luggage)
probably entered the Pentagon,
where we know that 125 Pentagon workers were killed.
Yet there are no photographs in public circulation of
the remains of these victims.

Summary

Proponents of the no-Boeing theory have made the following claims
about the debris from the crash:

There was no aircraft debris.

There was insufficient aircraft debris for a jetliner crash.

There was an absence of aircraft wreckage that should
have survived a jetliner crash, such as pieces of wings and tail.

The absence of signs of bodies, seats, and luggage in
photographs of the crash site prove that the attack plane
wasn't Flight 77.

Claim 1 is disproved by numerous post-attack photographs of the Pentagon.

Claim 2 is based on the unfounded assumptions
that the quantities of debris can be established from public evidence.

Claim 3 is invalidated by a review of the debris fields of
any number of jetliner crashes.

Claim 4 supposes that bodies, seats, and luggage should have
survived in easily recognized forms,
and that they would have ended up in places that were photographed.
However, the impact holes would have admitted an entire fuselage of 757
into the building, and there is no complete photographic
record of the interior wreckage available to the public.

Crash Test

The Sandia crash test of an F-4 into a concrete barrier
reduced the plane to rubble.
(
source)

Crash Examples

This photograph shows the crash site of a DC-8,
a jetliner of about the same size as a B-757

Fire Damage Example

This photograph shows what fire can do to an aircraft.
This was all that was left of a Boeing 747 after it caught fire
while landing.

Pentagon Debris Fields

This photograph shows a portion of the lawn near the heliport.
This photograph by Steve Riskus shows a foreshortened portion of the debris
field in front of the Pentagon's facade.
The far end of the heliport is about 100 feet
from the facade.

Debris Inside Pentagon

This photograph of the C-Ring punch-out hole shows
a significant quantity of aircraft debris.
This photograph shows scraps of metal,
some with green aircraft primer paint,
piled wrapped around a damaged column.

Debris in Yard

This photograph shows one of the larger pieces of debris on
the lawn in front of the facade.

Pentagon Facade Damage Fits a 757

The Pentagon attack resulted in extensive damage to the
facade corresponding roughly to the frontal profile of a 757.
The damaged area included extensive punctures on the first floor
and much smaller punctures on the second floor.

Punctured Walls Admitted Most of a 757

The portions of the Pentagon's facade punctured by the crash
are easily measured by combining data from several different photographs,
both before and after the collapse of the section.
Several
photographs by Jason Ingersoll
provide detailed views of right portions of the impact zone.
Other photographs show the left portions of the impact zone.
Together, these photographs show that the facade
was punctured over a wide swath on the first floor
and a much smaller extent on the second floor.

Measuring the punctured regions shows that the facade was
completely punctured for a width of 96 feet on the first floor
and 18 feet on the second floor.
Punctured areas were bounded by columns and floor slabs.
This is natural since the columns and floor slabs were
constructed of steel-reinforced concrete,
whereas the window bays spanning them were brick walls
reinforced with steel window frames and Kevlar mesh
as part of the renovation program.

On the first floor, the primary puncture extended from column 8 to column 18.
Three leaning objects in the first floor space left of the hole center
are often assumed to be displaced remains of columns 15, 16, and 17.
However,
this analysis
shows that those objects are more likely to be fallen pieces of
the second floor slab than columns.
Thus, it appears that the crash initially left a first floor hole
that extended unobstructed for 96 feet.
Surviving column 18 marked the rightmost extent of the hole,
but to the right of it is another hole extending to column 19.
Thus the total width of punctured walls on the first floor
was at least 105 feet.

On the second floor, the puncture extended from column 13 to column 15.
Photographs show a hanging object in the position of column 14.
This appears to consist in part of remains of the steel reinforcements
that were part of column 14.

Breached Limestone Marks Profile of 757's Wings

Beyond the areas of the punctured facade walls were extensive regions
in which the facade's limestone facing was breached.
Post-crash photographs show regions of missing limestone facing
from about four to eleven feet above the ground
and extending to at least 40 feet to the north of column line 8.

Photographs also show extensive damage to the south of the
impact punctures, with most of the damage to the south of column line 19
being above the first floor.

Although the damage beyond the impact punctures appears to be
consistent with the impact of the outer portions a 757's wings
in both degree and extent, many observers think that the impact
should have left a clear imprint of a 757's profile on the facade,
much as the impacts of 767s left their profiles in the Twin Towers.
This is not a persuasive argument against the crash of a 757:

The Twin Towers had curtain walls of box columns and spandrel plates
of steel between 1/4 and 3/4 inches thick at the crash zones,
and the walls were clad with delicate aluminum sheeting.
In contrast, the Pentagon had heavy masonry walls faced with limestone
slabs about 5 inches thick.
There is no reason to expect that the crash of a jetliner should
have produced similar impact scars in these very different buildings.

The physical integrity of the Pentagon attack plane on impact is unknown.
It is possible that either or both of the wings was severely damaged
by the impacts with the
lamp poles,
generator, and retaining walls
on its final approach.
Portions of the wings may have separated prior to impact,
changing their impact profiles.

Other events, such as the possible detonation
of a defensive weapons system described below,
could have further altered the crash profile.

Lateral Displacement of Tail Damage Suggests Explosion

One of the more persuasive arguments made against the crash
of a 757 is the apparent lack of facade damage above the second floor level
over the central impact region.
Photographs of the facade before the collapse show
no signs of damage to the limestone or windows above the second floor
impact punctures.
Because the aircraft approached at high speed,
the argument goes, the impact could not have significantly deflected
the vertical stabilizer (vertical part of the tail)
from a trajectory that would have forced it to
impact the building directly above the central hole
that admitted the fuselage.

The above argument is based on at least three assumptions:

The vertical tail section would have made an imprint in
or otherwise visibly damaged the limestone facade.

The impact of the plane would not have deflected the tail section
and caused it to impact some other part of the facade.

Some other event would not have deflected the tail section
and caused it to impact some other part of the facade.

Assumption 1 is intuitive, but there appears to be no experiment
or rigorous argument that establishes its validity.
The vertical tail sections of most jetliners are constructed of
lightweight materials, and do not have to support the kinds
of loads that the wing ends or elevators do.
There are even cases of vertical stabilizers breaking off
due to wake turbulence,
as was reported to happen in the crash of American Airlines Flight 587
on November 12, 2001.

Assumption 2 is also intuitive, because the tail section
would have had to undergo high accelerations
perpendicular to the flight path in order to deflect far
from the region above the impact hole center.
Whether the impact was insufficient to impart those accelerations,
however, has yet to be established.

Assumption 3 appears to have been overlooked by most
no-757-crash theorists.
Any of a number of events consistent with the available evidence
could have altered the trajectory of the vertical tail section
before or at the moment of impact.
Three possibilities are:

Stresses to the aircraft on its final approach caused
the vertical tail section to separate.
For example, the impacts of the engines with the generator trailer
and retaining wall might have sufficiently jolted the airframe
to break off the vertical stabilizer.

A bomb in the luggage hold exploded just as the
front of the fuselage was beginning to impact the facade.

A surface-to-air missile exploded on the aft starboard side
of the jetliner just as the nose was beginning to impact the facade.

Summary

Proponents of the no-Boeing theory have made the following claims
about the damage to the Pentagon's facade:

There was only one impact hole measuring no more than 18 feet across.

The impact hole was at most 65 feet across.

Standing columns remained where heavy 757 parts
should have obliterated them.

The hole was too small to accommodate wing ends and tail.

Claim 1 is based on the selective presentation of photographs
in which fire retardant spray obscures the entire first floor.
Claim 2 is based on the fallacy that the distance between
the expansion joints bounding the collapsed region of the facade
marked the maximum extent of impact punctures.
Post-crash photographs clearly show impact punctures extending
over twenty feet to the right and to the left of the expansion joints.

Claim 3 is based on the confusion of hanging sections
of the second floor for columns.
Claim 4 is true, but consistent with the crash of a 757
whose wing ends and tail are too light to puncture the
Pentagon's walls.

Facade Impact Punctures

This photograph by Jason Ingersoll
shows the impact hole center extending to the second floor
and punctured walls to its right.
Punctured walls to the left of the hole center
are obscured by smoke.
The cluster of three spools which appears close to the facade
is actually about 80 feet away from it,
to its right.
This study of facade damage builds a profile
of the region of breached walls by assembling
information from four different photographs.
This simulation shows a 757-200
colliding with the Pentagon's facade,
where the damage to the facade documented by photographs
is indicated by colors.

Damage Dimensions

This study measures the extent of punctured walls
(outlined in red) and breached limestone (outlined in green).

Breached Limestone

This photograph from the FEMA Report (Figure 3.8)
shows missing limestone
around and above windows to the left of the impact punctures.
This photograph from the FEMA Report (Figure 5.12)
shows impact damage
to the steel reinforced columns and brick walls
to the right of the impact center
following the removal of some of the limestone facing.
This photograph shows a larger view of damage to the
south of the impact center.

Tail Damage

This photograph shows scoring of the limestone
on the facade of the fourth floor.

Missile Batteries?

These photographs all show concrete structures with
open metal doors.
Do these structures contain some kind of defensive system?

757-200 Dimensions

These drawings depict a Boeing 757-200F, a freighter.
It has the same dimensions and shape as the passenger version
of the 757-200.

wing span

124 ft

10 in

length

155 ft

3 in

tail height (above ground)

44 ft

6 in

fuselage width

12 ft

4 in

Interior Damage is Consistent With a 757 Crash

Impact damage to the interior of the Pentagon was
primarily on the first floor,
and extended in a tapering swath from the first-floor facade puncture
to the vicinity of the C-Ring punch-out hole.

Floor Space Between Facade and C-Ring is Mostly Unobstructed

On the first and second floors,
the Pentagon has continuous interior space extending from the
facade to the inner-facing wall of the C-Ring,
joining the C-, D-, and E-Rings.
This is because the light wells between the C- and D-Rings
and between the D- and E-Rings only descend to the bottom of the third floor.
The only structural elements interrupting this space
are columns apparently spaced on 10-foot centers
along the direction perpendicular to the facade,
with each first-floor column having a square cross-section
measuring 21 inches on a side.

A figure on the left shows a path from the center of the facade
impact puncture to the center of the C-Ring punch-out hole.
That path could describe the path of fuselage debris from the
facade to the C-Ring wall, where it could have produced the
punch-out hole.
It shows that there was a narrow path for that debris
between the columns left standing by the crash.

C-Ring Punch-Out Hole Is in Path of Most Aircraft Mass

Many observers find the size of the punch-out hole peculiar
because it is small relative to a 757.
Measuring about 9 feet in diameter, it is much less than
the 12.5-foot diameter of a 757's fuselage.

However, the mass of a jetliner is not uniformly distributed
throughout its shape.
The fuselage of a 757 comprises only about a quarter of the
area of its frontal profile, but
makes up well over half of its mass.
The distribution of the mass within the fuselage is far from uniform.
Most of the structure is located in the lower third of the fuselage,
as are the heavy components such as the landing gear.

In a high-speed collision with a building,
only the parts of the aircraft with the greatest density and total mass,
such as the lower third of the fuselage,
could be expected to penetrate far into the building.
That part also has a small frontal profile --
approximately the size of the punch-out hole.

Column Damage Is What a Jetliner Would Produce

The last photograph in the right column shows a portion of the first
floor interior just north of the collapse zone.
Portions of the jet's left wing would have passed from right to left
in this area.
We can see the remains of several columns,
which originally had a square cross-section.
The impact apparently stripped away the concrete,
in several cases exposing the spiral steel reinforcement,
and in one case leaving only four strands of vertical rebar
anchored in the ceiling.
The photograph shows that all of the columns are bent in the same direction,
the same as throughout the crash zone.
The fact that the columns are bent in the same direction,
even 40 feet away from the impact center,
is indicative of the crash of an aircraft with large wings.

Summary

Proponents of the no-Boeing theory have made the following claims
about damage to the Pentagon's interior:

The C-Ring punchout hole could not have been made by a jetliner's nose

The C-Ring punchout hole could not have been made by a jetliner

Claim 1 may be true but is entirely irrelevant because
the nose of a jetliner is just the front end of the fuselage.
The fuselage, and particularly its lower half,
is the most massive part of a jetliner, and in a collision
its force would be concentrated in a small frontal profile,
much like a battering ram.

Most variants of Claim 2 incorrectly assume that there are
ground level masonry walls between the
C- and D-Rings, and D- and E-Rings.

Crash Trajectory

This illustration from FEMA's Report summarizes
the path of aircraft remains through the first-floor space
between the facade and the B-to-C-Ring courtyard.

Lack of Obstructions

This photograph shows the size and spacing of the columns in
the first-floor interior space between the facade and the C-Ring
This photograph from outside of the C-Ring punch-out hole
gives a sense of the lack of obstructions between the facade
and the C-Ring exterior wall.
One can see clear through the C-, D-, and E- Rings
to a pair of windows in the facade on the right
and the northmost end of the entry impact punctures on the left.

Debris Path

In this illustration, a gray line marks the path from
the center of the facade impact hole to the center of
the C-Ring punchout hole.
The path is unobstructed by columns that remained standing.

Interior Damage

This photograph was taken in the E Ring at the north end
of the crash zone looking south toward the collapsed section.

Damage to Surroundings Fits a 757

Eyewitness reports of the attack aircraft describe it
as clipping lamp-poles and a generator trailer
on its approach to the Pentagon.
Post-attack photographs corroborate these reports,
and show a pattern of damage fitting a Boeing 757.

Swath of Downed Lamp Poles Fits a 757's Wingspan

Photographs document the downing of five lamp-poles on and near
the highway overpass to the southwest of the Pentagon's crash zone.
The downed poles were in a swath running in a southwest to northeast
direction, with a centerline 38 degrees from the facade's normal.

Of the downed lamp poles whose condition was documented by photographs,
all appear to exhibit similar types of damage:
each was severed some distance from its base,
and is bent in an arc in the direction of the shear
over a much shorter distance.
This pattern of damage appears to be consistent with the high-speed
impact by the leading edges of wings.

Assuming that the downed lamp poles were clipped and toppled by an aircraft,
their pattern indicates that the aircraft had a wingspan of at least 100 feet.
The pattern of unmolested lamp poles and other objects,
such as the overhead sign,
indicates that the aircraft had a wingspan of not more than 130 feet.
(Since poles are probably designed to survive hurricane-force winds,
it is reasonable to exclude the idea that turbulence downed any lamp poles.)
Given a 757's 125-foot wingspan,
it fits the swath of damaged lamp poles.

Damage to Generator and Retaining Wall Fits a 757's Profile

Witnesses who observed the final moments of the crash
stated that the plane banked left
(some saying that the left wing hit the heliport)
and that its low-hanging engines hit objects on the way in:
the right engine hitting a generator trailer
and the left engine hitting a low retaining wall.
Post-crash photographs of the yard fit these accounts
and show a pattern of damage consistent with the paths of
the engines of a 757 based on the other data such as the
light-pole path.

A trailer containing a generator stood at the northwest corner
of the construction yard at the time of the attack.
In the attack, it was severely damaged,
sustaining a broad gouge on its northern end
and a narrow gouge on its top.
The generator was apparently pushed off its front stand,
leaving the front (north end) resting on the ground.

The narrow gouge appears to be slightly less than 45 degrees
away from the normal direction of the trailer's face.
Assuming that the trailer was oriented parallel to the fence
prior to the crash, the angle of the narrow gouge is consistent
with damage from a part of the same aircraft that clipped the lamp-poles.
The relative positions and shapes of the broad and narrow gouges
suggests they were caused by a 757's right engine,
and the first flap canoe beyond the right engine.
The distance between centerline of the narrow gouge
and the parallel line intersecting the center of the arc of the broad gouge
appears to be about the same as the distance between
the centerline of a 757's engine and the next flap canoe beyond the engine:
about 10 feet.

A low retaining wall surrounded a structure with a rectangular footprint
lying about 50 to 90 feet from the Pentagon's facade.
The structure has been described as part of a ventilation system.
Post-crash photographs show that the southwest corner of the
concrete retaining wall was gouged away.
The location of the gouge lies on the path of the left engine of
a 757 on a trajectory whose centerline intersects the facade
between column lines 13 and 14 and is 38 degrees from normal.

Positions of Cable Spools are Consistent With a 757 Crash

Post-crash photographs show five large cable spools in front
of the impact region of the Pentagon's facade.
One of the spools is toppled, while four are standing on their edges.
In most of these photographs, the spools appear very close to the facade,
making them appear to be obstacles in the
low-angled flight path of a jetliner into the Pentagon.
Since these photographs were taken from the highway about 500
feet west of the facade, the ground near the facade
is highly foreshortened in them.
An analysis of the spool positions using photographs from
different vantage points shows that the spool nearest the facade
was about 30 feet from it.
The other standing spools were about 80 feet away from the facade.

I estimate
below
that the wings impacted the facade at an average elevation
of about 8 feet, and that the plane was losing about a foot
of altitude for each 20 feet traveled.
The four standing spools appear to lie between the paths
of the two engines.
Assuming that the larger spools were 6 feet in diameter,
the flight path would have taken the bottom of the wings
and fuselage about two or three feet over the tops of
the larger spools.
The spool lying on its side is damaged,
and may have been hit by debris from the engine that hit
the retaining wall.

Summary

Proponents of the no-Boeing theory have made the following claims
about the damage to the Pentagon's surroundings:

Lamp-poles on the highway overpass were pulled out
or toppled the wrong way.

The damage to the generator could not have been produced by a 757's
engine and wing.

Spools standing in the yard should have been toppled by a 757.

Claim 1 is often repeated, but I have yet to find a single
coherent exposition of it.

One variant of Claim 2 holds that the engine could not have made
the broad gouge because the engine housing is too weak compared
to the generator trailer.
However, given the high speed of the impact, it would not
be surprising for an aluminum engine housing to carve a hole
through the trailer.
By way of analogy,
consider that a soft lead bullet can puncture a hole in a
1/8-inch-thick steel sign, given enough speed.

Most variants of Claim 3 appear to assume, incorrectly,
that the cable spools were very close to the facade,
or that they would be toppled by turbulence from the
fly-over of a 757.

Lamp-Pole Path

This illustration shows the positions of intact lamp poles
on and around the highway overpass,
indicating which ones were downed (yellow dots)
which were not (turquoise dots),
and the path of a Boeing 757 that would account for the downed poles.
This illustration from PentagonResearch.com
estimates the positions of lamp poles after they fell.

Lamp-Pole Damage

These photographs show the kind of damage that was inflicted
on some of the lamp poles.

Generator Damage

These photographs show the generator-trailer at the northeast
corner of the construction yard.
This illustration by Pierre Desmoulins
shows a 757 approaching the Pentagon at 38 degrees from normal.
This path takes the right engine over the north end of the generator.

Retaining Wall Damage

These two photographs both show damage to the southwest corner
of the retaining wall surrounding the structure
seen from above in the following photograph.
(
source)

Cable Spools

In most photographs, the cable spools appear deceptively
close to the building.

Specific Debris Matches a 757

Although most of the debris in photographs of the Pentagon
attack aftermath is too small to be identifiable,
as is typical of high-speed aircraft crashes,
some pieces are large enough to compare to known 757 components.
Of those pieces, all plausibly match parts of a 757,
and none fail to match 757 parts while matching
parts of some other aircraft.

Engine Parts Match a 757's Engines

Several photographs show a rotor adjacent to the Pentagon's facade
to the north of the impact zone.
The part has an outside diameter of about 2.5 feet
and turbine vanes just a few inches long.
Other parts behind the rotor appear to have a circular
cross-section with a diameter similar to the rotor.

The shape and dimensions of the rotor in the photographs match those
of several of the high-pressure rotors in a 757 engine.
(Boeing 757s are equipped either with the
Rolls-Royce RB 211-535E4, or the
Pratt & Whitney PW 2037 or PW 2040.)
While the largest rotor in such an engine -- the bypass fan --
is about 9 feet in diameter,
the high pressure compressor and turbine rotors are a fraction
of that dimension.

A photograph from inside of the Pentagon shows a scrap that appears
to be part of a jet engine's combustion chamber assembly.
The size, arrangement, and screw holes in the circular fuel nozzle ports
appear to match those of an RB211-535 -- a type of engine
used by Boeing 757s.

Landing Gear Parts Match a 757

Photographs of debris in the courtyard between
B- and C-Rings
show a damaged wheel hub surrounded by other apparent aircraft debris.
Numerous features in the photographed part match rear wheel
hubs of Boeing 757s --
the aspect ratio, the shape and number of oval perforations,
the bolts that lie just inside of the rim,
and the double ridge in the edge of the rim.
(The double ridge is visible in only about a tenth of the circumference
of the damaged hub.)

A photograph of the Pentagon's interior
shows a metal object with a cylindrical shaft
and structures on its end that were apparently formed
connections to other parts.
The part in the photograph has the same kinds of features as
the main rear landing gear strut on similar Boeing jets
such as 767s, and it may be an exact match for the strut of a 757.

Hull Piece Matches a 757 With American Airlines Colors

A scrap of aircraft photographed by Mark Faram on the lawn
just north of the crash site has a color scheme matching
an American Airlines jet:
silver, white, and red.

Closer examination of the scrap
and comparison of its decorations and rivet pattern
with that of an American Airlines 757-200 suggests that it matches
a section of the fuselage just aft of the starboard forward cabin door.
If the red marking is a part of the 'n' in 'American',
then the smooth edge on the rightmost end of the scrap
appears to be in the correct position for the door opening --
four rivet lines from the end of the 'n'.

Based on this argument, implying that the piece
could only have come from the forward right (starboard) side of a 757,
some observers have noted peculiarities about the piece.
How did it end up far to the left of the flight path?
Why does it show no signs of abrasion or burning?
Perhaps the argument is wrong, and the piece came from the
aft left (port) side of a 757.

Summary

Proponents of the no-Boeing theory have made the following claims
about the identification of aircraft parts in the rubble:

The rotor photographed north of the impact zone
is too small to be from a 757.

The rotor photographed north of the impact zone
is from an APU, SkyHawk A-3 engine, or other origin.

Only one engine was found.

Parts actually from or made to look like they were from a 757
were planted as part of the cover-up.

Claim 1 is based on the misapprehension that
all the rotors in a turbofan engine have the same diameter as the fan.

Variants of Claim 2 have been circulated by stories from sources
such as TomFlocco.com
which usually take the form of
an alleged aeronautical engineer claiming to have confirmed a match
between one of the parts in Pentagon photographs and a
part of an aircraft other than an Boeing 757.
I have yet to find such a story which meets even the most basic
journalistic standards.

Claim 3 is without basis since we have no way of knowing how many
or what engine pieces were found.

The best-known example of Claim 4 is the idea that
the hull piece described above had to be moved because its position
and condition were unnatural for the crash.
That may or may not have been true,
but even if it was, it could have been moved for reasons
having nothing to do with covering up the absence of a jetliner crash.

Engine Parts

The rotor in this photograph appears to be about 2.5 feet in diameter.
The object in the photograph with multiple round holes
appears to be the crumpled fragment of a jet engine's
combustion chamber casing.
The pattern of holes is similar to that of
the combustion chamber casing of a RB211-535.

Landing Gear Parts

A wheel hub in Pentagon crash debris photographs
matches the hubs of a 757's rear landing gear.
This piece of landing gear found in the
C-Ring near the exit hole has matching structures and
a similar shape to a 767's landing gear's main shaft (right),
the 767 having larger parts than a 757.
(Source of 767 part photograph:
PentagonResearch.com)

Hull Piece

A piece of debris photographed in the yard north of the crash site
appears to match the portion of an American Airlines 757
just aft of the front starboard cabin door.

Debris in C-Ring Courtyard

In this photograph showing debris outside the C-Ring punchout hole,
an apparent piece of aircraft debris that does not appear
to have been greatly distorted shows a curvature
corresponding to the 12-foot diameter of a 757.

The Attack Plane's Approach Is Consistent With a 757

The approach maneuver was, in several ways,
extreme and unusual for a jetliner.
According to reports the plane descended seven thousand feet
and turned over 270 degrees in the last three minutes
and then approached the west side of the Pentagon at a very
low altitude, clipping some obstacles and narrowly avoiding
others on its low-angle approach that ended with its
careening primarily into the Pentagon's first floor.

Many people have pointed out that the alleged pilot of Flight 77 --
Hani Hanjour -- did not have the requisite skills to perform the maneuvers.
Others have alleged that a Boeing 757 could not have flown the maneuvers.

Spiral Dive Is Well Within a 757's Capabilities

The Pentagon attack plane performed an impressive spiral dive before
making its low-altitude final approach into the Pentagon's west side.
CBS News described the maneuver as follows:

Radar shows that Flight 77 did a downward spiral,
turning almost a complete circle and dropping the
last 7000 feet in two-and-a-half minutes.

Air traffic controller Danielle O'Brien told ABC News:

The speed, the maneuverability, the way that he turned, we all thought
in the radar room, all of us experienced air-traffic controllers,
that that was a military plane. ...
You don't fly a 757 in that manner. It's unsafe.

Such a maneuver is not normal for jetliners,
but is it within the capabilities of a 757?
I will calculate the G force that the turning component
of the described maneuver would have imparted on the aircraft.
The G force produced by travel along a circular arc
can be calculated using the following formula:

If the plane were traveling at 400 miles per hour
it would travel 16.666 miles, or 26,821 meters, in 2.5 minutes.
Assuming it was traveling in a circular arc,
it would trace out 3/4ths of a circle with a 35,761-meter circumference,
giving a rotation radius of 5,691 meters and rotation speed of 0.3
rotations per minute.
Plugging those values into the above equation,
I obtain a centrifugal force of 0.5726 Gs.

Jetliners such as 757s are rated for accelerations of around two Gs,
but they may be able to survive much greater accelerations.
An IcelandAir 757-200 logged an incident in which it experienced
pitch accelerations of +3.95 Gs.

Final Approach Is Consistent With an Autopiloted 757

By all accounts the Pentagon attack plane approached the building's
west side from the southwest flying in a descending trajectory
that took it primarily into the Pentagon's first floor.
Details of the approach path can be inferred from damaged objects
such as the highway lamp poles and generator trailer.

The downed lamp poles indicate that the aircraft passed directly
over the highway overpass and cloverleaf intersection
southwest of the impact zone.
Two of the clipped lamp poles were on the northeast side of
the cloverleaf, about 600 feet from the impact zone center.
Assuming that the ground at the base of the poles was elevated
18 feet relative to the Pentagon's foundation,
and that the poles were clipped at a height of 20 feet,
the aircraft's wings were 38 feet higher than the foundation
at 600 feet before impact.
Assuming that the plane's wings were at an average elevation of
8 feet upon impact,
the plane would have lost 30 feet of altitude in 600 feet of travel,
averaging one foot of altitude for each 20 feet traveled.

These calculations suggest that the plane was flying within a wingspan
of the ground for at least its last thousand feet,
but not "inches from the ground" as some have stated.
Flying so close to the ground means the plane would have
been experiencing ground effect --
an increase in lift and decrease in drag produced by
proximity to the ground.
These effects result from the fact that the ground partially
blocks the trailing vortices produced by the wing,
decreasing the downwash and increasing the wing's effective angle of attack.

The influence of ground effect may have required the plane
to adjust its attitude in order to maintain a course toward
the Pentagon's first floor.
Since lift is proportional to angle of attack up to the
critical angle of attack (at which the wing stalls),
compensating for the increased lift due to ground effect
is simply a matter of adjusting the pitch downward to cancel
out the increased lift.
Although the adjustments required to maintain the
shallow angle of descent may have challenged a human pilot,
they would seem an easy task for a 757's autopilot,
with its ability to read instruments and adjust control surfaces
accordingly with great speed and accuracy.

Summary

Proponents of the no-Boeing theory have made the following claims
about the approach of the attack aircraft:

The spiral dive maneuver could not have been made by a jetliner.

The final approach was impossible due to ground effect.

Claim 1 is contradicted by the demonstrated performance
capabilities of a Boeing 757,
and Claim 2 fails to acknowledge that the increased lift
due to ground effect can be negated by lowering the angle of attack.

This illustration from
Pierre Desmoulins' website
estimates the slope of the aircraft's approach
using based on the positions of the clipped lamp-poles
and the heights at which they were clipped.

Ground Effect

This graph shows the reduction of induced drag
as a function of the proximity of an aircraft
to the ground.

Lift Function

This graph shows the relationship of lift
to angle of attack.

Suppressing Evidence of the Crash Serves the Cover-up

Evidence from the Pentagon crash that
would decisively resolve the question of whether Flight 77
was the attack plane
has been systematically suppressed by authorities,
such as the FBI.
Actions have included the following:

The
seizure of security videos
from the nearby Citgo gas station and Sheraton hotel
within minutes of the attack,
and their refusal to release those videos.

A failure to release recordings of
security video cameras thought to ring the Pentagon
or traffic monitoring video cameras along the nearby highways
maintained by the Virginia Department of Transportation.

A failure to release photographs
of the Pentagon's interior prior to removal of debris.

A failure to disclose the fate of
aircraft debris collected at the Pentagon,
and their failure to document or disclose the results
of any attempts to identify the aircraft parts.

This behavior is consistent with three different motives
on the parts of the those responsible for suppression
and destruction of evidence.

An institutional penchant for secrecy,
amplified by the atmosphere of national emergency
produced by the attack

A desire to suppress evidence that would disprove
the crash of Flight 77

A desire to suppress evidence that would prove
the crash of Flight 77

People who fail to grasp the role of disinformation
in the cover-up will tend to overlook Motive 3
and attribute the suspicious actions to Motive 2.
However, as I point out in the
Booby Trap article,
an analysis of the history of the 9/11 Truth Movement
demonstrates the value of the no-jetliner theories
in sidelining challenges to the official story
as the product of lunatic conspiracy theorists.

Conclusion

In this essay I asked what conclusions about the Pentagon attack
were supported by physical evidence --
primarily post-crash photographs of the site.
I found that, in every aspect I considered,
this evidence comports with the crash of a Boeing 757.
At the same time,
the evidence does not conclusively prove that the aircraft was a 757,
much less that it was Flight 77.
However, that lack of conclusiveness should not be surprising given the
systematic suppression of evidence by authorities.